


Ephemeral

by CharWright5



Category: SK8 the Infinity (Anime)
Genre: Alpha Kikuchi Tadashi, Alpha/Beta/Omega Dynamics, Begging, Biting, Come Eating, Comeplay, Fingers in Mouth, Heat Sex, Knotting, M/M, Mating Cycles/In Heat, Mentions of one-sided Ainosuke/ Langa, Multiple Orgasms, Omega Shindo Ainosuke, Possessive Tadashi, Rough Sex, Squirting, Vaginal Fingering, Vaginal Sex, Wet & Messy, omegas have vaginas
Language: English
Status: Completed
Published: 2021-03-12
Updated: 2021-03-12
Packaged: 2021-03-20 10:20:41
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 3,546
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/30003390
Author URL: https://archiveofourown.org/users/CharWright5/pseuds/CharWright5
Summary: Nothing was forever, especially not moments like this when Tadashi was actually allowed to be with Ainosuke the way he truly wanted to be.
Relationships: Kikuchi Tadashi/Shindo Ainosuke | Adam
Comments: 5
Kudos: 67





	Ephemeral

**Author's Note:**

> Me: *joins new fandom and immediately posts two omegaverse fics in a single day for it*
> 
> Um, as stated in the tags, this features Omegas with vaginas, so if that's not you're thing, click out. There will also be mentions of Adam's flirtations/ actions towards Langa during episode five so, yeah, warning there, too. Also, this was honestly supposed to be soft sweet lazy fingering in the morning, idk wtf happened...
> 
> I wanna dedicate this to the little SK8 channel in my server and everyone there being so chill and awesome as we all crashed into this fandom and yell-cried together. Love y'all!

The sun shining through the window brought with it another layer of warmth to the haze they were both still seemingly stuck in. Despite taking suppressants, Ainosuke’s Omega nature was so strong that it was impossible to completely eradicate his Heat, meaning he still suffered from overwhelming arousal and a need to be knotted. It wasn’t so bad that it was debilitating or caused him to miss work--or, god forbid, miss a race at S--and he wasn’t reduced to a crying, soaking, pleading mess the way stereotypes and porn made Heat-addled Omegas out to be. But it was enough to be distracting and annoying and cause him to seek out relief that would only come from being knotted.

Tadashi figured it was just lucky that he was the one Ainosuke had come to rely on over the years to help take care of said annoyance, that he happened to be an Alpha with a knot capable of bringing the Omega some relief.

He sure as hell wasn’t about to let Ainosuke seek it elsewhere, not after having to witness him practically try to climb and mount that Snow fucker at S.

Never again.

Tadashi let out a possessive rumble, half atop Ainosuke as the Omega lay prone on his back. His legs were splayed open, thighs covered in a combination of his own slick, the liquid he’d squirted out, and Tadashi’s come, remnants of an all night fuck fest. Fatigue had settled into their bones, making them lazy, but the scent of Ainosuke was still strong in the air, that hint of Heat and spice that meant he wasn’t one-hundred percent relieved. He could go to work like this, sure. He could slap on a couple patches on his scent glands and no one would know the difference.

Not that Tadashi would let him.

Not that Ainosuke would allow Tadashi the privilege of bossing him around or telling him what he could or could not do.

Really, the only time Tadashi was in charge was during these moments, when Ainosuke’s Omega nature took over during his Heat, when he naturally submitted to the Alpha. His instincts wouldn’t allow him not to.

Even still those instincts had Ainosuke’s head tilting back, a soft purr escaping him, and Tadashi took what was on offer for the… god, he’d lost count. Both of their bodies were littered with all kinds of marks, his hand sliding up a well toned body, passing bites and hickeys and bruises until he got to finger shaped ones around the Omega’s throat. At one point early on, Tadashi had pinned him to the bed with a hand around his neck, shoving Ainosuke’s face into the pillow during the throes of things, and Ainosuke had gone entirely limp at it, had gotten wetter, his cunt clamping down even harder as he tried to pull Tadashi’s knot inside and keep it there.

His fingers pressed against a bruise as his tongue lapped at a bite mark on the other side. Not permanent. It would never be that way between them. But that didn’t stop Tadashi from imagining, as he had since they were kids playing pretend. He let himself fall into the fantasy that this was real, that they could have this every day, that he could sink his teeth into that scent gland currently pumping out pleased pheromones and that his bite would scar over, be a permanent mark to all around Ainosuke to back the fuck off.

Another growl rumbled up from his chest and he let his teeth slot into the divots he’d previously left, his pelvis rocking against Ainosuke’s hip where he was half-straddling him. The Omega gasped, the sound shifting into a groan, the smell of his slick getting stronger as his arousal began to build again.

“Tadashi,” Ainosuke moaned, shivering, his breathing growing heavier. Yet that haze of fatigue made the syllables slur, his tongue heavy. “Again?”

Tadashi’s hand automatically moved down from where he’d been caressing the Omega’s neck, curving over his pubis. He was still soaked down there, his clit hard from arousal, the bare skin of his mound sticking to Tadashi’s palm as he cupped him.

“Feels hot,” Tadashi murmured, moving his lips up to nip at Ainosuke’s earlobe. “You sure you’re okay to?”

Ainosuke’s answer was to spread his legs even further open, nodding. “Please.”

Fuck, that single word got him hotter than anything, his own cock stiffening against the hollow of Ainosuke’s hip. His middle finger flicked against Ainosuke’s clit, the nub still so wet, and Ainosuke gasped again, his hips rocking as though trying to gain more.

“Good boy,” Tadashi praised and Ainosuke groaned in response as the Omega in him soaked it up, his body going limp against the mattress.

His finger traced over Ainosuke’s lower lips in a tease and he raised his head to find Ainosuke biting his bottom lip, a hand shoving into his own messy blue hair. The man was always so immaculately put together, so determined to be the picture of professional perfection. Even at S, under his “Adam” persona, his hair was perfect, countless products used to make it stand the way he wanted.

Not during his Heat.

During his Heat, his superficiality went out the window and he no longer cared about whatever image he was projecting, no longer cared that his hair remained the way he had styled it. Meaning he didn’t care that there were currently clumps standing up straight or falling into his eyes, that he looked absolutely wild. He didn’t care about the flush over his cheeks or the sweat on his skin or the marks on his neck. He would later when his head cleared and he got a good look at himself, when he chewed Tadashi out for getting carried away and now he had to cover them all up. But for the moment, he was the picture of lazy, hazy Omega, his eyes cloudy with arousal still, his body loose and open and ready to be filled once more.

He was fucking beautiful like this and Tadashi felt his chest get tight, knowing that he was the only one to ever see Ainosuke like this, knowing that it was never to be in the way he wanted it to be. He was just a loyal dog serving his master.

But if being a dog got him what he wanted, even if briefly, he’d greedily steal it like a starving mangy mutt.

“Spread yourself open for me,” he rumbled, shifting so he was laying on his side, propped up on an elbow. He pulled his hand away from Ainosuke’s cunt, tracing up over his bare mound, between the lines of his defined abdominal muscles.

Ainosuke flushed, the muscle in his jaw clenching as the Omega in him warred with the boss part. Yet his hands still moved down, his fingers still spread open his lips, his legs still opened up as best they could, right one bent up so he bare himself all the more.

“Please,” he repeated, whispered, red eyes hazy and pleading, and Tadashi felt too weak to the beauty before him when he said it so sweetly and with such humility.

“I’ll take care of you,” Tadashi promised, words ghosting against Ainosuke’s lips as he leaned down. His hand slipped down once more and this time, it was to the wet open cunt of his Omega, his childhood friend who’d sneakily stolen his first kiss the first time Tadashi had bandaged up cuts from skateboarding.

“So wet for me,” he murmured, middle finger tracing over his soaked clit, dipping down to pass over his entrance.

Ainosuke gasped then whined when he wasn’t entered, hips rocking needily. “Just for you,” he mumbled in response, eyes fluttering shut. He was only ever honest in these times, when the haze of Heat dissolved the filter, when it eradicated the walls that those words would ordinarily be hidden behind.

“You’re such a good boy for me,” Tadashi praised, his middle finger so easily sliding inside, drawing out a long groan. He was so wet, so hot, so sticky with come and his own slick juices, body still so open. It was practically nothing to pull out and slide two fingers inside. “You take me so well.”

Ainosuke panted, whimpered, his fingers clenching onto his own thighs as he tried to hold himself open. “‘Dashi,” he whined, eyes once again open, locked onto Tadashi’s.

“I’ve got you,” he promised, curving his fingers as his thumb pressed against Ainosuke’s clit, finding that spot inside to bring out the most pleasure.

The reaction was immediate, Ainosuke’s back arching off the bed and his hands slipping away to slam against the mattress as he cried out. “More!” he practically demanded. “I need more, please, ‘Dashi, more.”

Tadashi didn’t even think to hesitate or refuse. Instead, he began to work his fingers against Ainosuke’s g-spot, hearing the way his slick and Tadashi’s come squelched inside of him, hearing the way Ainosuke began panting harder. A hand curved on Tadashi’s shoulder from the back, manicured nails digging in as the Omega sought something to ground himself, Ainosuke’s other free hand going to grab his own chest. Tadashi lowered his head to suckle at his free nipple, all the while his fingers continued to play with that sensitive place inside of him.

God, this hadn’t been his intention, truly. He’d wanted to be soft, gentle, knowing how rough he’d been during the night. Despite the haze of Heat clouding Ainosuke’s brain in that moment, it would eventually go away and the pain and irritation would come in, making for a grumpy Omega that was sure to make the next week of Tadashi’s life hell as payback.

Part of him truly believed it was worth it. Maybe he was a masochist. Maybe he just knew the trade-off was alright in his books, knowing that he’d pay any price to be with Ainosuke this way.

His fingers continued to rub against that spot, building Ainosuke up, the Omega now damn near thrashing on the bed. His hand had left his chest in favor of reaching up to clutch at the pillow beneath his head, his body rocking up and down, hips shaking as they sought more while also trying to get away from how overwhelming it all was. Tadashi moved so that his body was laying atop one of Ainosuke’s spread legs, keeping him open and exposed, keeping that easy access as he kept going.

“Wanna make you squirt,” he rumbled, the Alpha in him leaking into his voice. “Wanna see you soak the bed again.”

Ainosuke keened, head falling back, knowing that regardless of his thoughts, it was gonna happen anyway. Tadashi had already made him squirt twice during the night, loved to see him make a huge mess of things. There was a huge puddle beneath them from it and he was glad that Ainosuke had had the foresight to have Tadashi put down the Heat protector on the mattress before they’d gotten started.

The entire bed would be deemed useless if he hadn’t.

Even in that moment, he wasn’t entirely sure if the plastic sheets below the silken ones they currently lay on had done enough to protect it.

Ainosuke’s cunt squeezed around his fingers, drawing his attention back to the… well, the task at hand really, and Tadashi focused on his current job, raising his head up enough to mouth at the side of Ainosuke’s neck once more. The Omega’s entire being was trembling, his breathing shaky and shallow, and it was only a matter of time before…

Tadashi sank his teeth into his scent gland, the taste of Ainosuke exploding on his tongue, crisp apple and sharp cinnamon. Ainosuke practically wailed as his back bowed off the bed and Tadashi peeked down his body to see contracting muscles and spasming thighs. He slipped his fingers free to swipe over Ainosuke’s clit repeatedly as he squirted, watching the liquid fly, a mix of clear Omega slick and white Alpha come. His instincts weren’t all that thrilled with seeing his seed leave, even if logically he knew that Ainosuke was on birth control, that no matter how long he kept it inside, it would never do the job.

Ainosuke would never allow it to happen.

He ignored the part of him that mourned that, instead moving between the Omega’s splayed legs. Ainosuke still looked out of it, floating, body quivering from his orgasm. Peering down, Tadashi could see his cunt quivering, his open hole bright red as it opened and closed, clutching around nothing.

He could solve that easily.

His cock was rock hard as he shoved it inside, the Omega crying out as he arched off the bed once more, hands slapping against the mattress. Tadashi hauled him onto his lap, driving his cock deeper, until he could feel the wetness of Ainosuke’s clit against his damp pubic hair. He let the course hairs rub against the sensitive nub, ignoring any objections or the way the Omega was pushing at him weakly.

“Wait, wait, wait, I’m still--” Ainosuke’s words were choked off with a sob as Tadashi flicked his fingers against his clit. His walls shuddered and clenched around the hard length impaling him, another orgasm wracking his body. “Ah, shit, ‘Dashi, _please_.”

Tadashi honestly had no idea what he was asking for. Not that it mattered much to him in that moment. His brain was pure Alpha at that moment, growling and demanding that he mate and breed and possess.

“One more,” he growled out, moving so he was up on his knees, Ainosuke’s body half-rolled back and making him groan. “One more time and you’ll be sated.”

Ainosuke whined, clawing at Tadashi’s torso. Yet there was something in his eyes that said he understood, he agreed, he wanted and needed, he trusted Tadashi to take care of him.

And with that, Tadashi pulled back and slammed into him, making Ainosuke cry out.

“Oh fuck, there, yes!”

Tadashi smirked, feral and with too much teeth. “I know, Ai, I know,” he murmured, reassuring, reaching down to stroke the Omega’s cheek, relishing the way Ainosuke leaned into the touch. “I’ve got you. I know what you like.”

A whimper then Ainosuke turned his head to nip at the flesh of Tadashi’s palm, before mouthing along until he could suck one of Tadashi’s fingers inside of his mouth. He let out a pleased hum, eyes rolling back as they fluttered closed.

“Tastes like us,” he murmured, sounding almost drunk from it, hands moving to clutch at Tadashi’s wrist to make sure he didn’t pull away, now suckling on two of the Alpha’s fingers. “Tastes so good.”

Tadashi pulled out, pulled his hand away as he rolled the Omega down onto his back once more, ignoring the distressed whines he got. Instead, he slipped his fingers back inside of Ainosuke’s cunt to scoop out more of their combined juices to feed to the Omega, letting him truly get a taste.

Ainosuke groaned, the sound muffled even as it increased in volume when Tadashi’s cock slid back inside of him, filling him from both ends. His eyes rolled to the back of his head as his body went limp, as the Omega in him felt at ease over being so full, the way he was meant to be. Ainosuke out of Heat would fight against his nature, was always trying to prove that his Dynamic didn’t mean shit when it came to being in charge, when it came to running the company, when it came to his dealings with DIET. But Ainosuke during his Heat was pure Omega and Tadashi knew exactly how to take care of his needs no matter the time of month.

“Taking me so well, Ai,” Tadashi purred, rolling his hips, pressing inside as deeply as he could, grinding his pubic bone against Ainosuke’s clit and making him whimper. “You always take me so well. Such a good Omega.”

Ainosuke smiled around the fingers in his mouth, purring loudly, his own hips rolling right back, his walls squeezing around Tadashi’s cock.

“You want my knot?”

Ainosuke nodded, sucking hard on Tadashi’s fingers as his cunt practically sucked on his cock, trying to take everything inside the way an Omega should. “Wan’ id,” he slurred, eyes getting cloudier, scent growing stronger. “Pwease.”

Tadashi moved so he was laying atop the Omega, pressing their bodies together, driving into him even harder, even stronger. “Good boy,” he praised once more, slipping his fingers free to card them through Ainosuke’s hair. “Such a good boy. You really are the best Omega.”

The Omega in question was practically melting into the bed, the praise having him purring non-stop, eyes fluttering shut as he smiled widely. Tadashi knew that Ainosuke’s life had him getting torn apart metaphorically by those above him, by the aunties who showed love through violence, fucking his head up. It caused Ainosuke to lash out in the worst ways, to continue the cycle, to show his own love in equally--if not more--violent ways.

Tadashi was determined to undo that, to show him that he deserved _real_ love that didn’t involve physical harm or cut downs. Ainosuke deserved praise, deserved to feel good, deserved all the best things. Sometimes Tadashi believed he was part of the reason why Ainosuke was the way he was, why the Adam persona acted out in such an aggressive manner, and this was his way to make up for that, to fix things, to fix _Ainosuke_.

Until his Heat broke and Ainosuke went back to the way he had been.

Still, Tadashi continued to heap the love and praise onto his Omega in the hopes that it’ll sink in, that one day Ainosuke would believe it.

“I--” Ainosuke huffed, and Tadashi cupped his face, pressing their foreheads together. Ainosuke covered his hand with his own, a slight wince on his face as the pleasure became overwhelming, as he drew closer to his peak. “I need--please--I want--”

“It’s okay,” Tadashi assured, giving him a smile, nuzzling their noses. “I’ve got you. I’ll knot you.”

Ainosuke shook his head, swallowed hard, his inner-walls shuddering. “Need, also need,” he tried again, cut off by a whimper as Tadashi shifted to curve his hand over Ainosuke’s mound once again. “Mark me. Want you to mark me.”

Tadashi breathed out a swear, his eyes shutting tight. Everything in him demanded he gave in to his Omega’s desires, demanded he do just that. His teeth practically ached for it, to sink in deep, break the skin with the intention of leaving a permanent mark, to bond them together permanently in a way that even the Shindo Clan couldn’t sever.

That even Snow couldn’t get between.

But he knew it wasn’t what Ainosuke truly wanted, that it was just his Omega instincts reaching out to the closest available Alpha, confusing pheromones and Heat lust for actual love and a lifetime bond. It didn’t matter that Tadashi wanted it, had wanted it for years. It would never happen because Ainosuke would never let it happen.

But they had this, this time together, these moments, and Tadashi was taking advantage, leaning down to suck at Ainosuke’s scent gland to simulate the sting of a bite, to give him a weakened version of what his Omega brain thought it wanted.

And as predicted, Ainosuke cried out, his legs wrapping around Tadashi’s waist to hold him close, arms clinging to him. His every breath was a harsh huff, his body trembling, walls quivering, and fuck, Tadashi’s knot wsa rapidly expanding as Ainosuke’s body tried so hard to pull him inside and keep him there.

“Last chance to cha--”

“Fuckin’ _knot me_ ,” Ainosuke demanded, snarling, and like a trigger going off, Tadashi’s knot pulsed straight to being full expanded, locking him inside. His fingers began rubbing circles on Ainosuke’s clit, slick and wet and so soft beneath his touch. Ainosuke’s back arched as his head fell back, an arm reaching up to the headboard as he panted, hips rolling and walls rippling and body trembling until…

“ _Ah fuck!!_ ”

Tadashi could feel everything inside get wetter and with the way the Omega was squeezing, milking him, his own orgasm hit him hard. He shot off inside, lamenting the way his seed wouldn’t do anything even as the Alpha part of him was glad to be marking his Omega’s inside, filling him up all over again.

He raised his head to find Ainosuke laying with his eyes closed, smile on his face as his scent grew warm with satisfaction, body languid. His chest was still heaving as his breathing evened out, skin flushed and sweat soaked once more, his hair even messier than it had been.

Absolutely beautiful, exquisite.

Tadashi’s chest hurt from it. It ached from the knowledge that this wasn’t his, that one day, Ainosuke was going to Mate someone else and Tadashi would never be blessed with this image ever again.

Until then…

He lowered his head and pressed their lips together, a silent promise that until the day Ainosuke was taken from him, he’d continue to be his loyal dog and serve his master in all ways.


End file.
